If a document concerns embodiments which are covered by several subgroups dependent on a higher hierarchy group, the following rules apply:

the specific technical information relevant for some of the subgroups is classified in all said subgroups, for example a fiber rearranging device located in the nozzle of a headbox is classified in D21F 1/0018 and D21F 1/028;

if relevant, the structural association (e.g. the combination) of the elements covered by the subgroups is classified in the head group;

analogously, if generic technical information common to all of the subgroups is disclosed and only schematic embodiments of the specific subgroup embodiments are represented, the documents is classified in the head group only.

Glossary of terms

In this place, the following terms or expressions are used with the meaning indicated:

Screens or fabrics made from plastic materials and useable for forming paper webs in a paper machine by separating fibers from an aqueous suspension or also if usable for drying a paper web in the drying section of a paper machine.

Fabrics comprising two separate layers (paper side layer and machine side layer) and a system of binding yarns interconnecting said layers, the binding yarns can also contribute to the forming of the paper side layer (known as sheet support binding (SSB)).

Watermarking in general, watermarking devices acting on the fibrous suspension or layer while on the forming screen or wire; producing special forming wires or screens for making watermarks; separate watermark elements.